Focal areas of hemorrhagic necrosis will be produced in the brains of monkeys previously given Evans blue and I131 labeled albumin. The animals will be killed 24 hrs. later and the edematous tissue separated by gross dissection. Edema fluid will be isolated from this tissue by centrifugation. The following analyses will be performed: sodium, chloride, potassium, I131, dye, osmolarity, total protein and cellulose acetate electrophoresis. The results will be compared with a terminal sample of blood serum. Obtained from the same animal and an attempt will be made to define the chemical composition of the edema fluid in relation to serum. These results will then be correlated with total tissue analysis and an attempt will be made to define the chemical pathogenesis of this experimental form of cerebral edema.